The present invention relates to a longitudinal adjuster for a vehicle seat having a freely pivotable backrest, with the longitudinal adjuster having a first seat rail, a second seat rail in relation to which the first seat rail can be slid in the longitudinal direction, and a memory device which is assigned to the first seat rail, interacts with the second seat rail and stores a set longitudinal seat position which can be left by way of a longitudinal displacement of the vehicle seat when the backrest pivots freely, and resumed when the backrest pivots back.
DE 42 01 829 A1 discloses a longitudinal adjuster of the above-described type, in which a drag lever is entrained during the normal longitudinal adjustment of the vehicle seat. When the backrest pivots freely, the drag lever is lowered and engages in the fixed seat rail so that the vehicle seat can be slid forward from this stored longitudinal position. When it returns to the stored longitudinal position, the locking of the longitudinal adjuster is triggered when the drag lever is run onto, so that the vehicle seat is locked again in this longitudinal position.
One aspect of the present invention is the provision of an improved longitudinal adjuster. In accordance with one aspect of the present invention, a longitudinal adjuster, which is for a vehicle seat having a freely pivotable backrest, includes a first seat rail, a second seat rail in relation to which the first seat rail can be slid in the longitudinal direction, and a memory device which is assigned to the first seat rail, interacts with the second seat rail and stores/remembers a longitudinal seat position which can be left by way of a longitudinal displacement of the vehicle seat when the backrest pivots freely, and resumed when the backrest pivots back, wherein a displacement measuring device, which can be operatively connected to the second seat rail, and a control signal generator, which can move in relation to the displacement measuring device, are provided. The relative movement of the control signal generator with respect to the displacement measuring device from a home position corresponds to the longitudinal displacement of the vehicle seat which has occurred. The control signal generator experiences, at the latest when the stored/remembered longitudinal seat position is reached, a control torque and then the control signal generator actuates at least one locking element which interacts with the second seat rail.
By virtue of the fact that a displacement measuring device which can be operatively connected to the second seat rail and a control signal generator which can move in relation to the displacement measuring device are provided, with the relative movement of the control signal generator with respect to the displacement measuring device from a home position representing the longitudinal displacement which has occurred, the control signal generator experiencing, at the latest when the stored/remembered longitudinal seat position is reached (i.e. when this position is reached or for example just before), a control torque and then actuating at least one locking element which interacts with the second seat rail so that the further longitudinal displacement is blocked, the sensing of the displacement and the locking effect are decoupled from one another. The forces which are necessary for the locking effect between the seat rails, i.e. the forces which are necessary for stopping the movement of the first seat rail, are, in contrast to the prior art, not taken up by the means for sensing displacement in a measuring area but rather by a separate, actuated locking element in a load area so that plastic components which can be manufactured cost-effectively can be used for the control area and measuring area, while components made of metal can be used for the load area. The control area does not need to be completely integrated into the measuring area but rather can be separated from it somewhat, which increases the versatility of the actuation possibilities.
The actual locking of the longitudinal adjuster is carried out by a separate locking device which is configured to absorb crashing forces, unlocks when the longitudinal adjuster is directly triggered and locks the longitudinal adjuster again in the newly set longitudinal seat position. This locking device is to be distinguished from the locking elements in the load area. This locking device is in principle independent of the memory device, but is generally indirectly coupled by way of the triggering of the longitudinal adjuster. For example, there may be a coupling for resetting the memory device.
A positioning lever which can, for example, be pivoted, slid or can be moved in some other way and is mounted so as to stay with the housing is preferably provided as a locking element, the positioning lever pivoting, sliding or moving out of the memory device when it is acted on by the control signal generator and interacting directly with the second seat rail, for example by way of a locking nose. A plurality of these positioning levers whose locking noses are then preferably at different distances from the preferably common pivoting axis have the advantage that the effective pitch of the second seat rail is reduced in accordance with the number of the positioning levers in the manner of the vernier principle so that one of the positioning levers is sure to be effective, i.e. stops the movement of the vehicle seat.
When a smaller number of positioning levers are to be provided, a positioning lever can be replaced with a nonmovable place holder made of plastic and shaped like the positioning lever being replaced. The positioning levers are preferably capable of being actuated individually and can be lifted out together, for example by virtue of the fact that the control signal generator acts on them in the one pivoting direction by way of individual tongues and in the other pivoting direction by way of a common bracket.
In one preferred embodiment, the control signal generator which is embodied as a spindle nut runs on a spindle of the displacement measuring device, which permits the distance which is covered from the stored/remembered longitudinal seat position to be stored precisely. In order to define the home position of the control signal generator and to transmit the control torque, the control signal generator on the one hand, and a block of the displacement measuring device on the other hand, each preferably have a stop face. The stop faces move into a position in which they bear against one another when the stored/remembered longitudinal seat position is reached, and in doing so transmit the control torque. The distance traveled is preferably sensed by way of a rotatably mounted running wheel which interacts with the second seat rail in a switchable/disassociatable fashion and is operatively connected to the displacement measuring device. As the running wheel does not have to apply any locking forces, it can interact with the second seat rail in a frictionally locking fashion or with fine toothing.
The running wheel is preferably mounted on a pivotable switching lever or a multi-element lever arrangement which disconnects the running wheel from the second seat rail in order to store a newly set/new remembered longitudinal seat position, that is to say in order to reset the memory device. A reset spring of the displacement measuring device which is preferably provided then moves the control signal generator into its home position. So that there is as far as possible no play, and therefore no slip, in that state in which the running wheel is seated on the second seat rail, a contact pressure spring is preferably provided. The contact pressure spring presses the running wheel against the second seat rail, for example by acting on the switching lever.
The entire memory device, with the exception of projecting locking elements and possible control elements for resetting the memory device, is preferably arranged within an installation space which is defined by the first seat rail, that is to say embodied as a type of module. In comparison with the prior art, this provides a large saving in terms of installation space with a memory device which is arranged outside the seat rails.
An actuation device which, when the longitudinal adjuster is directly triggered, resets the memory device in order to permit a new longitudinal seat position (e.g., a new remembered longitudinal position) to be stored is preferably provided, in which case, when the backrest pivots freely, the memory device is decoupled without resetting so that the remembered longitudinal seat position which is set remains stored and can be found again. The actuation device can be mounted on the first seat rail above the memory device, that is to say in the direct vicinity of the memory device, which simplifies the resetting of the memory device. In the process, the actuation device can at the same time form a component of the unlocking system of the longitudinal adjuster by virtue of the fact that it supports, for example, components which are necessary for it. During the free pivoting, the actuation device can then preferably unlock the locking device.
The invention is preferably used for vehicle seats of two-door motor vehicles, but can also be used with other vehicle seats.